Inflow conduit for ventricular assist device

Abstract

An inflow conduit of a ventricular assist device configured to prevent formation of recirculation and stagnation zones as well as collapse due to external forces or pump induced suction can be rigid and have a funnel like shape with an elbow to accommodate a patient anatomy. Stiffening elements and pressure sensing devices can also be provided associated with the inflow conduit.

1. An apical cannula member comprising:
 a. a first portion having a tip attachable to a heart ventricle; 
 b. a second portion having a graft end connectable to a vascular graft member; 
 c. a bend portion intermediate said tip and said graft end; and 
 d. wherein said bend portion begins with a generally circular cross section, has a first transition to a cross section having a flattened oval shape, and then has a second transition from said flattened oval shape back to a generally circular cross section. 
 
   
   
     2. The apical cannula of  claim 1  wherein said first transition further comprises said flattened oval shape characterized by a flattening of top and bottom sides of the apical cannula as defined by a plane through a centerline of said apical cannula. 
   
   
     3. The apical cannula of  claim 2  wherein said second transition further comprises said flattened oval shape characterized by a flattening of left and right sides of the apical cannula, said left and right sides being perpendicular to said plane. 
   
   
     4. The apical cannula of  claim 1  further comprising said first portion having a generally straight region between said tip and said bend portion, said generally straight region having a generally circular cross section. 
   
   
     5. The apical cannula of  claim 4  further comprising said generally straight region having a decreasing diameter from said tip to said bend portion. 
   
   
     6. The apical cannula of  claim 4  further comprising said generally straight region having a median diameter which is generally equal to a diameter of a hole which can be cored into said heart ventricle to accommodate insertion of said tip thereinto for attachment of said apical cannula. 
   
   
     7. The apical cannula of  claim 6  further comprising said tip having a diameter which does not exceed said median diameter by more than about 0.5 centimeters. 
   
   
     8. The apical cannula of  claim 4  further comprising said generally straight region having a generally circular cross section at least at along portion thereof which is insertable into said hole in said ventricle. 
   
   
     9. The apical cannula of  claim 4  wherein said bend portion is substantially rigid. 
   
   
     10. The apical cannula member of  claim 1  further comprising a pressure sensor attached to or incorporated into at least one of said first portion, said second portion, and said bend portion. 
   
   
     11. The apical cannula member of  claim 10  further comprising a support ring which attaches to an outer surface of the apical cannula, said pressure sensor attached to said support ring and secured thereby to said outer surface. 
   
   
     12. The apical cannula of  claim 11  wherein said support ring is attached to said first portion of said apical cannula. 
   
   
     13. The apical cannula member of  claim 1  wherein at least one of said first and second portions has a wall portion which expands and contracts responsive to pressure changes in said apical cannula. 
   
   
     14. The apical cannula member of  claim 13  wherein said wall portion further comprises:
 a. a thin inner wall member which stretches and contracts responsive said pressure; and 
 b. a corrugated strip outer wall member which lengthens and shortens responsive to said pressure. 
 
   
   
     15. The apical cannula of  claim 14  wherein said wall portion further comprises a spacer between said thin inner wall member and said corrugated strip outer wall member. 
   
   
     16. The apical cannula of  claim 14  wherein said wall portion further comprises:
 a. said corrugated strip wall member having a first end and a second end, and notches therein between said first and second ends; 
 b. an end-housing affixed to said second end of said corrugated strip wall member; 
 c. a wire having a fixed end attached to said first end of said corrugated strip wall member, said wire extending around said corrugated strip wall member through said notches, said wire having a free end movably disposed in said end-housing resulting in relative motion between said free end and said end-housing responsive to pressure changes in said apical cannula; and 
 d. wherein said relative motion is measured using said free end and said end-housing as a linearly variable displacement transducer. 
 
   
   
     17. An apical cannula comprising:
 a. a first portion having a tip attachable to a heart ventricle; 
 b. a second portion having a graft end connectable to a vascular graft member; 
 c. a bend portion intermediate said tip and said graft end; and 
 d. at least one of said first and second portions has a wall portion which expands and contracts responsive to pressure changes in said apical cannula, wherein said wall portion further comprises: 
 e. a thin inner wall member which stretches and contracts responsive said pressure; 
 f. a corrugated strip outer wall member which lengthens and shortens responsive to said pressure; and 
 g. a spacer between said thin inner wall member and said corrugated strip outer wall member. 
 
   
   
     18. An apical cannula of comprising:
 a. a first portion having a tip attachable to a heart ventricle; 
 b. a second portion having a graft end connectable to a vascular graft member; 
 c. a bend portion intermediate said tip and said graft end; and 
 d. at least one of said first and second portions has a wall portion which expands and contracts responsive to pressure changes in said apical cannula, wherein said wall portion further comprises: 
 e. a thin inner wall member which stretches and contracts responsive said pressure; 
 f. a corrugated strip outer wall member which lengthens and shortens responsive to said pressure, said corrugated strip wall member having a first end and a second end, and notches therein between said first and second ends; 
 g. an end-housing affixed to said second end of said corrugated strip wall member; 
 h. a wire having a fixed end attached to said first end of said corrugated strip wall member, said wire extending around said corrugated strip wall member through said notches, said wire having a free end movably disposed in said end-housing resulting in relative motion between said free end and said end-housing responsive to pressure changes in said apical cannula; and 
 i. wherein said relative motion is measured using said free end and said end-housing as a linearly variable displacement transducer.